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Posts tagged Skamania County

Mount St. Helens in the Cascade Volcanic Arc, USA

May 12th, 2010 Category: Mountains, Volcanoes

USA - April 28th, 2010

USA - April 28th, 2010

Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States, visible just below the center of this orthorectified image.

Mount St. Helens is most famous for its catastrophic eruption on May 18, 1980, at 8:32 am PDT which was the deadliest and most economically destructive volcanic event in the history of the United States.

The volcano is located in the Cascade Range and is part of the Cascade Volcanic Arc, a segment of the Pacific Ring of Fire that includes over 160 active volcanoes. This volcano is well known for its ash explosions and pyroclastic flows.

As with most other volcanoes in the Cascade Range, Mount St. Helens is a large eruptive cone consisting of lava rock interlayered with ash, pumice, and other deposits. The mountain includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the dacite domes formed the previous summit, and off its northern flank sat the smaller Goat Rocks dome. Both were destroyed in the 1980 eruption.

Mount Hood and Lake Bonneville, Western USA – May 9th, 2010

45.5N 121.5W

May 9th, 2010 Category: Image of the day, Rivers, Volcanoes

USA - April 28th, 2010

USA - April 28th, 2010

Mount Hood, standing out above the surrounding peaks of the Cascade Range in the lower right quadrant of this orthorectified image, is a stratovolcano in the Cascade Volcanic Arc of northern Oregon. It is located about 50 miles (80 km) east-southeast of Portland, on the border between Clackamas and Hood River counties.

The exact height assigned to Mount Hood’s snow-covered peak has varied over its history. Modern sources point to different heights: 11,249 feet (3,429 m) based on the 1991 U.S. National Geodetic Survey and 11,240 feet (3,426 m) based on a 1993 scientific expedition. Regardless, it is the highest mountain in Oregon and the fourth-highest in the Cascade Range.

Visible to the north of the volcano is Lake Bonneville, a reservoir on the Columbia River shared by the U.S. states of Oregon (south) and Washington (north). It was created in 1937 with the construction of Bonneville Dam. The reservoir stretches between it and the Dalles Dam, upstream. It lies in parts of three counties in Oregon (Multnomah, Hood River, Wasco) and two in Washington (Skamania, Klickitat).